Effect of different irrigation regimes and salinity on wheat yield in Gorgon region

Effect of water quantity and quality on wheat grain yield and yield components were studied in northeast of Golestan province. The treatments included four water levels with 50(W1), 75(W2), 100(W3) and 125(W4) percent of crop water requirement and four water quality with salinity of 1.6 (S1), 7.9 (S2), 10.8 (S3) and 13.6 (S4) ds/m. The experiments were evaluated using a randomized complete block design with split-plot layout which considered water quantity as main plots and water quality as subplots, with three replications. The results revealed that water quantity and quality were significant on wheat yield. Different irrigation depths and salinity levels were not significant on spike number per m2 and were significant on 1000-grain weight and grain/spike. The seasonal water consumption by wheat increased when water quantity increased, while it decreased when irrigation water salinity increased. For example, in treatment W4, treatment S4 consumed 88% water as of S1 treatment. Seasonal distribution of water content and salinity in soil profile showed that water content increased when irrigation water salinity was increased. The highest salt concentration occurred in surface soil layer. In all treatments, using saline water accounts for the improvement of water use efficiency (WUE) when fresh water is considered, comparing to total applied water (fresh saline). So that, in W3S4 treatment, WUE for total water use was equal to 9.8 while for fresh water it was 20.9 kg.ha-1.mm-1.